Provided is an organic tin-free cationic electrodeposition coating composition which does not contain organic tin compound and can sustain a superior coating curability under currently used baking conditions, and to a catalyst for the composition. A catalyst for electrodeposition coating composition containing a bismuth compound (A), wherein: the bismuth compound is a compound having a ligand prepared from a -diketone represented by Chemical Formula (1) is provided. ##STR00001##
(wherein, a plurality of R.sup.1 are the same or different from each other and represent a hydrocarbon group, and a number of total carbon atoms in two R.sup.1 is 4 or larger)

Provided is an organic tin-free cationic electrodeposition coating composition which does not contain organic tin compound and can sustain a superior coating curability under currently used baking conditions, and to a catalyst for the composition. A catalyst for electrodeposition coating composition containing a bismuth compound (A), wherein: the bismuth compound is a compound having a ligand prepared from a -diketone represented by Chemical Formula (1) is provided.

##STR00001##

(wherein, a plurality of R.sup.1 are the same or different from each other and represent a hydrocarbon group, and a number of total carbon atoms in two R.sup.1 is 4 or larger)

Disclosed herein are methods for reprocessing polyurethane compositions such as polyurethane foams. The method comprises introducing a polyurethane composition into a compounding device, heating the polyurethane composition to an effective bond-exchange temperature, and compounding the polyurethane composition for an effective bond-exchange time.